unitedhealthcare. ♪ (train horn) vo: wherever our trains go, the economy comes to life. norfolk southern. one line, infinite possibilities. >>> all right. just minutes away our "the situation room" special report, obama care under fire, but first this "impact your world." >>> country singer clint black is known for his signature cowboy hat and his classic sound. ♪ >>> but beyond the music, black is supporting the fight against a disease called rhett's syndrome. >> my niece courtney, my brother kevin's daughter was afflicted with this and lost her battle with it at age 16. >> reporter: the syndrome almost always affects girls, usually diagnosed by 18 months. children can't communicate and require constant care. there is no cure -- yet. >> i think the human knee-jerk reaction is to look away, because it's really hard to see, and it's real suffering, but the more i see, the more i see the families and how hard they fight, the more i realize, you know, we can't look away. we have to look. we have to see. >> reporter: black is the ambassador for the foundation. hi efforts h